1. Field of the Invention
The present invention relates to a method and device for setting speed of data transmission.
2. Description of the Related Art
Digital transmission is only possible if a transmitting facsimile machine and a remote facsimile machine are set to the same transmission speed. Conventionally, to insure that two facsimile machines are set to a transmission speed common to both, facsimile machines follow a series of operations internationally standardized by the Consultative Committee in International Telegraphy and Telephony (CCITT). First, a transmitting facsimile machine will dial a remote facsimile machine. Once the telephone circuit is connected, the remote facsimile machine will transmit a digital identification signal (DIS) at 300 bps to the transmitting facsimile machine. The DIS includes information on capabilities of the remote facsimile machine such as transmission speeds at which the remote facsimile machine is capable of receiving facsimile data, the resolution, that is, super fine, fine, or standard, of the remote facsimile machine, and method of digital compression. The transmitting facsimile machine receives the DIS and compares its own capabilities with contents of the DIS. The transmitting facsimile machine then selects capabilities common to both itself and the remote facsimile machine and transmits these conditions to the remote facsimile machine in a digital command signal (DCS) also at 300 bps. In this way, the transmission speed, resolution, and method of data compression for transmission between the two facsimile machines are set.
There has been known a facsimile machine capable of transmission and reception with a computer system. The facsimile machine is provided with an interface, such as an RS232C interface, which allows the facsimile machine to be connected to the computer system. With this configuration, image data from the computer system can be transmitted to the facsimile machine, which can then transmit the image data over a telephone circuit to a remote facsimile machine. Also, the facsimile machine can transmit image data received from a remote facsimile machine to the computer system, which uses the image data for various purposes.
When a facsimile machine is connected to a computer system in this manner, the user normally uses the same facsimile machine and the same computer. Therefore, the user accomplishes transmission between the two by setting the transmission speed of the interface, for example, the RS232C interface, to the same speed as the transmission speed of the interface of the facsimile machine.